Hi,
Am I correct in understanding that the LC29Hxx UART will be burned out by a 3v3 MCU without level shifting? This seems an odd quirk on a 3v3 system.
Thanks
but Mozihao puts resistors on his board… @splee has modified, other e.g. Mahdi no.
The diagram seems to suggest direct connection, but the VDDIO says absolute maximum 3.08v on GPIO for the module. I’ve also seen the voltage divider setup as well as a diode with a pullup to 2v8 on the LC29H side. Quectel also suggest that a 1k resistor in series could potentially cause some issues?
So to confirm, 3v3 will burn the GPIO but a voltage divider should be enough to bring it in line? Or is it better to go with the diode setup to avoid potential issues with excessive series resistance?
The commonly used Mozihao board has a 1k resistor in series on the TX line, and a resistive divider on the RX line. I had a problem with the resistor on the TX line not being able to drive some esp32 pins and removed it to fix the problem. I left the resistive divider on the RX as that appears to be needed to reduce the voltage into the module.